Our objective is to achieve a detailed understanding of the relaxin molecule through studies of the chemical structure of relaxin-related peptides, the mechanisms of their biosynthesis and their mode of interaction with specific cellular receptors in target cells, particularly fibroblasts and uterine myometrial cells. The project will involve sequence analysis of relaxins an relaxin precursors from several species including man, chemical synthesis of relaxin and chemical analogues thereof, structure-function studies and X-ray crystallographic analyses. Since relaxin is a structural homologue of insulin, examination of hybrid molecules formed between the 2 hormones using natural and synthetic chains will be of particular interest. It is anticipated that these studies will shed light on the physiological role of relaxin and may thereby indicate possible therapeutic applications of the knowledge obtained in disorders of reproductive function and in connective tissue diseases. The studies should also increase our fundamental understanding of the structure and function of the insulin molecule, and as such have potential relevance to diabetes.